1. Field of the Invention
The ability to detect and diagnose cancer through the identification of tumor markers is an area of widespread interest. Tumor markers are substances, typically proteins, glycoproteins, polysaccharides, and the like, which are produced by the tumor cells and characteristic thereof. Often, the tumor marker is produced by normal cells as well as tumor cells. In the tumor cell, however, the production has become atypical. For example, production of the tumor marker may be greatly increased in the cancer cells. In some cases, intracellular enzymes may be released into blood circulation when the cell becomes malignant. In other cases, the tumor marker remains on the cell surface and can be localized.
The identification of novel tumor markers is thus desirable for the detection and diagnosis of cancer.
2. Description of the Prior Art
A particular enzyme identified as thioesterase II has been identified in rat mammary glands. This enzyme functions in the production of medium-length fatty acids. See Libertini and Smith (1978) J. Biol. Chem. 253:1393-1401; Smith and Ryan (1979) J. Biol. Chem. 254:8932-8936; Smith (1980) J. Dairy Sci. 63:337-352; Nolin et al. (1982) J. Endocr. 94:251-256; Pasco et al. (1982) Exp. Cell Res. 141:313-324; and Smith et al. (1983) Biochim. J. 212:155-159. Cells from adenocarcinomas in rats were found to produce thioesterase II. Libertini et al. (1980) Biochimica, Biophysica, Acta. 618:185-191. Thioesterase II has not previously been identified in humans. The identification of particular tumor markers is known. See, e.g., U.S. Pat. No. 4,317,877 to Balis et al. which concerns assays for the detection of oncofoetal deoxythimidine kinase.